Field of the Invention
The present invention relates to a numerical controller for controlling a machine tool, and more particularly, to a numerical controller capable of preventing wrong machining after a machining condition change.
Description of the Related Art
There is a method in which a machining path is drawn to be checked by simulated operation of a machining program before actual machining is performed by a machine tool. This drawing of the machining path based on the simulated operation is called check drawing. In an actual machining after the check drawing, a current position is displayed on the drawn path so that the machining state can be understood.
Japanese Patent Application Laid-Open No. 2002-91523 discloses an automatic programming technique capable of easily modifying an NC program and starting a simulation based on drawing processing at a modified portion. Further, Japanese Patent Application Laid-Open No. 2013-69231 discloses a technique capable of displaying one or more past feedback trajectories stored in a tool trajectory storage section in a superposed manner and accurately visually analyzing trajectory shape changes before and after a machining condition change.
Normally, check drawing is performed once just before actual machining. If the machining program or machining conditions, including a parameter, correction amount, and machining state, are changed or manual intervention is performed during the actual machining, the machining path may sometimes change thereafter. In such a case, there is a possibility of an operator continuing the operation as it is, thereby causing wrong machining or breakage of a tool, workpiece, etc.
The technique described in Japanese Patent Application Laid-Open No. 2002-91523 is characterized in that the drawing processing is performed as the NC program is modified in programming. According to this technique, therefore, the drawing processing cannot be performed based on a change of conditions during actual machining. On the other hand, the technique described in Japanese Patent Application Laid-Open No. 2013-69231 is characterized in that machining paths executed in two or more different machining conditions are superposed. According to this technique, therefore, the drawing processing cannot be performed in case where an unmachined path changes according to machining conditions.